Description
c-ares is an asynchronous resolver library. From 1.32.3 through 1.34.4, there is a use-after-free in read_answers() when process_answer() may re-enqueue a query either due to a DNS Cookie Failure or when the upstream server does not properly support EDNS, or possibly on TCP queries if the remote closed the connection immediately after a response. If there was an issue trying to put that new transaction on the wire, it would close the connection handle, but read_answers() was still expecting the connection handle to be available to possibly dequeue other responses. In theory a remote attacker might be able to trigger this by flooding the target with ICMP UNREACHABLE packets if they also control the upstream nameserver and can return a result with one of those conditions, this has been untested. Otherwise only a local attacker might be able to change system behavior to make send()/write() return a failure condition. This vulnerability is fixed in 1.34.5.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| c-ares | c-ares | >= 1.32.3, < 1.34.5 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | c-ares | 1.34.5-1 | — |
| Debian 13 | c-ares | 1.34.5-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.04 | c-ares | 1.34.4-2.1ubuntu0.1 | USN-7477-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | nodejs +5 | 1:22.15.0-1.el10_0 | RHSA-2025:7502 |
| RHEL 10 | nodejs-npm | 1:10.9.2-1.22.15.0.1.el10_0 | RHSA-2025:7502 |
| RHEL 9 | nodejs +3 | 1:20.19.1-1.module+el9.6.0+23053+4195b0b2 | RHSA-2025:7433, RHSA-2025:7426 |
| RHEL 9 | nodejs-libs | 1:22.15.0-1.module+el9.6.0+23062+9e7801b9 | RHSA-2025:7433 |
| RHEL 9 | nodejs-nodemon | 3.0.1-1.module+el9.3.0.z+20478+84a9f781 | RHSA-2025:7433, RHSA-2025:7426 |
| RHEL 9 | nodejs-packaging +1 | 2021.06-4.module+el9.3.0+19518+63aad52d | RHSA-2025:7433, RHSA-2025:7426 |
| RHEL 9 | npm | 1:10.8.2-1.20.19.1.1.module+el9.6.0+23053+4195b0b2 | RHSA-2025:7433, RHSA-2025:7426 |
| RHEL 9 | v8-12.4-devel | 3:12.4.254.21-1.22.15.0.1.module+el9.6.0+23062+9e7801b9 | RHSA-2025:7433 |
| RHEL 8 | nodejs +3 | 1:20.19.1-1.module+el8.10.0+23054+5431297f | RHSA-2025:4461, RHSA-2025:4459 |
| RHEL 8 | nodejs-libs | 1:22.15.0-1.module+el8.10.0+23068+28ff2340 | RHSA-2025:4459 |
| RHEL 8 | nodejs-nodemon | 3.0.1-1.module+el8.10.0+22904+d0fedeff | RHSA-2025:4461, RHSA-2025:4459 |
| RHEL 8 | nodejs-packaging +1 | 2021.06-4.module+el8.10.0+22904+d0fedeff | RHSA-2025:4461, RHSA-2025:4459 |
| RHEL 8 | npm | 1:10.8.2-1.20.19.1.1.module+el8.10.0+23054+5431297f | RHSA-2025:4461, RHSA-2025:4459 |
| RHEL 8 | v8-12.4-devel | 3:12.4.254.21-1.22.15.0.1.module+el8.10.0+23068+28ff2340 | RHSA-2025:4459 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9.4 EUS | nodejs +3 | 1:20.18.2-2.module+el9.4.0+23089+aaa18a20 | RHSA-2025:7537 |
| RHEL 9.4 EUS | nodejs-nodemon | 3.0.1-1.module+el9.3.0.z+20478+84a9f781 | RHSA-2025:7537 |
| RHEL 9.4 EUS | nodejs-packaging +1 | 2021.06-4.module+el9.3.0+19518+63aad52d | RHSA-2025:7537 |
| RHEL 9.4 EUS | npm | 1:10.8.2-1.20.18.2.2.module+el9.4.0+23089+aaa18a20 | RHSA-2025:7537 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | nodejs +4 | 1:22.15.0-1.el10_0 | ALSA-2025:7502 |
| AlmaLinux 10 | nodejs-npm | 1:10.9.2-1.22.15.0.1.el10_0 | ALSA-2025:7502 |
| AlmaLinux 9 | nodejs +3 | 1:20.19.1-1.module_el9.6.0+163+d268fe53 | ALSA-2025:7433, ALSA-2025:7426 |
| AlmaLinux 9 | nodejs-libs | 1:22.15.0-1.module_el9.6.0+164+2d89b8ed | ALSA-2025:7433 |
| AlmaLinux 9 | nodejs-nodemon | 3.0.1-1.module_el9.5.0+125+8dc38870 | ALSA-2025:7433, ALSA-2025:7426 |
| AlmaLinux 9 | nodejs-packaging +1 | 2021.06-4.module_el9.5.0+139+09296491 | ALSA-2025:7433, ALSA-2025:7426 |
| AlmaLinux 9 | npm | 1:10.8.2-1.20.19.1.1.module_el9.6.0+163+d268fe53 | ALSA-2025:7433, ALSA-2025:7426 |
| AlmaLinux 9 | v8-12.4-devel | 3:12.4.254.21-1.22.15.0.1.module_el9.6.0+164+2d89b8ed | ALSA-2025:7433 |
| AlmaLinux 8 | nodejs +3 | 1:20.19.1-1.module_el8.10.0+3987+dbda4426 | ALSA-2025:4461, ALSA-2025:4459 |
| AlmaLinux 8 | nodejs-libs | 1:22.15.0-1.module_el8.10.0+3986+a908e756 | ALSA-2025:4459 |
| AlmaLinux 8 | nodejs-nodemon | 3.0.1-1.module_el8.10.0+3982+85c136aa | ALSA-2025:4461, ALSA-2025:4459 |
| AlmaLinux 8 | nodejs-packaging | 2021.06-4.module_el8.10.0+3961+6a788e57 | ALSA-2025:4461, ALSA-2025:4459 |
| AlmaLinux 8 | nodejs-packaging-bundler | 2021.06-4.module_el8.10.0+3958+472a6467 | ALSA-2025:4461, ALSA-2025:4459 |
| AlmaLinux 8 | npm | 1:10.8.2-1.20.19.1.1.module_el8.10.0+3987+dbda4426 | ALSA-2025:4461, ALSA-2025:4459 |
| AlmaLinux 8 | v8-12.4-devel | 3:12.4.254.21-1.22.15.0.1.module_el8.10.0+3986+a908e756 | ALSA-2025:4459 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 9 | nodejs-nodemon | 3.0.1-1.module+el9.5.0+31770+0da7192d | RLSA-2025:7433, RLSA-2025:7426 |
| Rocky Linux 9 | nodejs-packaging | 2021.06-4.module+el9.5.0+31770+0da7192d | RLSA-2025:7433, RLSA-2025:7426 |
| Rocky Linux 8 | nodejs | 1:20.19.1-1.module+el8.10.0+1972+57cf735f | RLSA-2025:4461, RLSA-2025:4459 |
| Rocky Linux 8 | nodejs-nodemon | 3.0.1-1.module+el8.9.0+1760+903d54b9 | RLSA-2025:4461, RLSA-2025:4459 |
| Rocky Linux 8 | nodejs-packaging | 2021.06-4.module+el8.9.0+1419+1f26ef47 | RLSA-2025:4461, RLSA-2025:4459 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
| SLES 15 SP6 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
| SLES 15 SP5 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
| SLES 15 SP4 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 SP6 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
| SLES for SAP 15 SP5 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
| SLES for SAP 15 SP4 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
| SLE Micro 6.1 | c-ares | 1.34.8-slfo.1.1_1.1 | SUSE-SU-2026:23414-1 |
| SLE Micro 6.0 | c-ares | 1.34.8-1.1 | SUSE-SU-2026:23364-1 |
| SLE Micro 5.5 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
| SLE Micro 5.4 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
| SLE Micro 5.3 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
| SLE HPC 15 SP5 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
| SLE HPC 15 SP4 | c-ares | 1.34.8-150000.3.29.1 | SUSE-SU-2026:4021-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | c-ares | 1.34.5-1.1 | openSUSE-SU-2025:14977-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | c-ares | 1.34.5-r0 | — |
| Alpine v3.23 | c-ares | 1.34.5-r0 | — |
| Alpine v3.22 | c-ares | 1.34.5-r0 | — |
| Alpine v3.21 | c-ares | 1.34.5-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | nodejs20 +4 | 1:20.19.0-1.amzn2023.0.1 | ALAS2023-2025-942 |
| Amazon Linux 2023 | nodejs20-npm | 1:10.8.2-1.20.19.0.1.amzn2023.0.1 | ALAS2023-2025-942 |
| Amazon Linux 2023 | v8-11.3-devel | 3:11.3.244.8-1.20.19.0.1.amzn2023.0.1 | ALAS2023-2025-942 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | fluent-bit | 3.1.9-4 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | nodejs +4 | 1:22.16.0-1.el10_0 | ELSA-2025-7502 |
| Oracle Linux 10 | nodejs-npm | 1:10.9.2-1.22.16.0.1.el10_0 | ELSA-2025-7502 |
| Oracle Linux 9 | nodejs +3 | 1:20.19.1-1.module+el9.6.0+90590+fd42b52a | ELSA-2025-7433, ELSA-2025-7426 |
| Oracle Linux 9 | nodejs-libs | 1:22.15.0-1.module+el9.6.0+90588+1a9ecb62 | ELSA-2025-7433 |
| Oracle Linux 9 | nodejs-nodemon | 3.0.1-1.module+el9.3.0+90066+12d4a8d7 | ELSA-2025-7433, ELSA-2025-7426 |
| Oracle Linux 9 | nodejs-packaging +1 | 2021.06-4.module+el9.3.0+90066+12d4a8d7 | ELSA-2025-7433, ELSA-2025-7426 |
| Oracle Linux 9 | npm | 1:10.8.2-1.20.19.1.1.module+el9.6.0+90590+fd42b52a | ELSA-2025-7433, ELSA-2025-7426 |
| Oracle Linux 9 | v8-12.4-devel | 3:12.4.254.21-1.22.15.0.1.module+el9.6.0+90588+1a9ecb62 | ELSA-2025-7433 |
| Oracle Linux 8 | nodejs +3 | 1:20.19.1-1.module+el8.10.0+90560+49d7a1eb | ELSA-2025-4461, ELSA-2025-4459 |
| Oracle Linux 8 | nodejs-libs | 1:22.15.0-1.module+el8.10.0+90558+f3d29a46 | ELSA-2025-4459 |
| Oracle Linux 8 | nodejs-nodemon | 3.0.1-1.module+el8.10.0+90558+f3d29a46 | ELSA-2025-4461, ELSA-2025-4459 |
| Oracle Linux 8 | nodejs-packaging +1 | 2021.06-4.module+el8.10.0+90558+f3d29a46 | ELSA-2025-4461, ELSA-2025-4459 |
| Oracle Linux 8 | npm | 1:10.8.2-1.20.19.1.1.module+el8.10.0+90560+49d7a1eb | ELSA-2025-4461, ELSA-2025-4459 |
| Oracle Linux 8 | v8-12.4-devel | 3:12.4.254.21-1.22.15.0.1.module+el8.10.0+90558+f3d29a46 | ELSA-2025-4459 |
Advisories 28
- ALSA-2025:7502 Moderate: nodejs22 security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:7426 Moderate: nodejs:20 security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:7433 Important: nodejs:22 security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:4461 Moderate: nodejs:20 security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:4459 Important: nodejs:22 security update AlmaLinux Security Advisories · Oct 29, 2026
- SUSE-SU-2026:23414-1 Security update for c-ares SUSE / openSUSE Security Updates · Sep 14, 2026
- SUSE-SU-2026:4021-1 Security update for c-ares SUSE / openSUSE Security Updates · Sep 13, 2026
- SUSE-SU-2026:23364-1 Security update for c-ares SUSE / openSUSE Security Updates · Sep 10, 2026
- WID-SEC-2025-0943 Red Hat Enterprise Linux (node.js): Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 9, 2026
- RHSA-2025:7537 Red Hat Security Advisory: nodejs:20 security update Red Hat Security Advisories (RHSA) · Sep 9, 2026
- RHSA-2025:7502 Red Hat Security Advisory: nodejs22 security update Red Hat Security Advisories (RHSA) · Sep 9, 2026
- RHSA-2025:7433 Red Hat Security Advisory: nodejs:22 security update Red Hat Security Advisories (RHSA) · Sep 9, 2026
- RHSA-2025:7426 Red Hat Security Advisory: nodejs:20 security update Red Hat Security Advisories (RHSA) · Sep 9, 2026
- RHSA-2025:4459 Red Hat Security Advisory: nodejs:22 security update Red Hat Security Advisories (RHSA) · Sep 9, 2026
- RHSA-2025:4461 Red Hat Security Advisory: nodejs:20 security update Red Hat Security Advisories (RHSA) · Sep 9, 2026
- openSUSE-SU-2025:14977-1 c-ares-devel-1.34.5-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2025-1850 Xerox FreeFlow Print Server: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff BSI CERT-Bund (WID) · Nov 17, 2025
- USN-7477-1 c-ares vulnerability Ubuntu Security Notices (USN) · Oct 13, 2025
- RLSA-2025:4461 Moderate: nodejs:20 security update Rocky Linux Security Advisories · Jul 29, 2025
- RLSA-2025:4459 Important: nodejs:22 security update Rocky Linux Security Advisories · Jul 29, 2025
- RLSA-2025:7426 Moderate: nodejs:20 security update Rocky Linux Security Advisories · Jul 29, 2025
- RLSA-2025:7433 Important: nodejs:22 security update Rocky Linux Security Advisories · Jul 29, 2025
- ELSA-2025-7502 Moderate: nodejs22 security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Jun 30, 2025
- ELSA-2025-7433 Important: nodejs:22 security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · May 22, 2025
- ELSA-2025-7426 Moderate: nodejs:20 security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · May 21, 2025
- ELSA-2025-4459 Important: nodejs:22 security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · May 5, 2025
- ELSA-2025-4461 Moderate: nodejs:20 security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · May 5, 2025
- ALAS2023-2025-942 Moderate: nodejs20 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Apr 29, 2025